Significance Various types of adjuvants are used experimentally in nonhuman primates for vaccine research. Identifying optimal immunogens while minimizing adverse side effects would be beneficial to the research primates. Objectives The objective of this study is to examine the safety and efficacy of five test adjuvants in long-tailed macaques (Macaca fascicularis). Results The adjuvants evaluated were Montanide, TiterMax Gold, Immumax, and two different preparations of a biodegradable gel matrix. The adjuvants were combined with 5mg bovine serum albumin (BSA), a weak antigen. Positive (alum) and negative (saline) controls were included for a total of seven study groups. The safety of each preparation was evaluated by monitoring local tissue reaction. The injection sites were visually assessed daily for evidence of swelling or redness. Efficacy was evaluated through serum ELISA anti-BSA antibody titer at 2 weeks post-injection and 2 weeks after the booster. Muscle biopsies of the injection sites were collected to examine cellular infiltrate at 2 weeks post-injection and 2 weeks after the booster. There was a large amount of variation in the daily observation data within the different study groups. However, Montanide was the most benign of the test adjuvants with respect to local tissue irritation and inflammation. Both control groups al so elicited relatively little local tissue reaction while the TiterMax Gold, Immumax and both biodegradable matrix preparations caused relatively more irritation and inflammation. The Montanide, TiterMax Gold, and Immumax preparations elicited a significant antibody response to BSA at both time points. The alum, saline and biodegradable matrix preparations did not elicit an antibody response to BSA. Future Directions These results will be used to help investigators choose optimal adjuvants for their experiments. KEY WORDS vaccines, adjuvants, testing FUNDING NIH Grant RR00169